Small pectoral muscle

Synonyms

Latin: Pectoralis minor muscle
English: minor pectoral muscle

Synergist: pectoralis major muscle
Antagonist: M. trapezius

course

Approach: Raven beak extension (processus coracoideus)

Origin: 2nd - 5th rib, lateral to the cartilage-bone border

Innervation: Nn. pectorales med., C (6) - 8, Th1

anatomy

The small pectoral muscle lies below the large pectoral muscle (M. pectoralis major). It has its origin at the front of the 3-5. Rib about 6cm from the sternum. From there it runs to the raven beak extension (Coracoid process) on the shoulder blade.

He is nervously supplied by the Medial pectoral nerve and the Lateral pectoral nerve. Both are nerves of the Brachial plexus, a plexus of nerves from the spinal nerves that leave the spinal cord at the level of the 5th cervical vertebra to the 1st thoracic vertebra.
The subclavian vein and artery run below the insertion of the small pectoral muscle. Among other things, it serves to supply the arm with blood. The brachial plexus is wrapped around the subclavian artery.

function

The pectoralis minor (Pectoralis minor muscle) pulls the shoulder blade, along its grain, forwards and downwards. By its attachment to the anterior upper part of the shoulder blade and its origin at the middle part of the 3-5. Ribs, when the muscle is shortened, the shoulder blade is pulled forward and down.
When the shoulder is fixed, the pectoralis minor muscle serves as a Auxiliary respiratory muscles.

Fixation of the shoulder blade leads to a kind of reversal of the pulling direction. That is, instead of pulling the shoulder blade forward and down, the 3-5. Rib pulled upwards and outwards to help expand the chest during inspiration.
A fixation of the shoulder blade can be achieved by a Support the armse.g. on your knees, be brought about.

Optimal support of the diaphragm by the auxiliary breathing muscles can best be guaranteed by slightly bending the upper body and supporting the arms.

Common diseases of the pectoralis minor

The pectoralis minor muscle is often tense due to unfavorable postures in everyday life.

Muscle pectoralis major strain

Generally, a strain arises from Overstretching of the muscle. Sudden excessively strong movements or unnatural / unfamiliar ranges of movement often lead to a muscle strain. At the histological level, no tissue damage can be found in the event of a strain.

Likewise, a Overload cause strains in isometric training methods. In this type of exercise, the muscle tenses to prevent the fibers from lengthening. However, if the muscle is too weak to hold the position, overstretching can occur.

Examples of isometric training of the pectoralis minor muscle: exercises performed very slowly on the butterfly machine. Due to the slow execution, the muscles have to tense each other again and again so that the weight slowly lowers and the fibers gradually lengthen. Overloading and jerky lengthening can lead to a strain.

Tension of the small pectoral muscle

Muscle tension is something very common. If they last longer, the tension can become hardening, which is also called Myogelosis are designated. The doctor can feel these well within the muscles. They often arise as a result of overexertion or poor posture.

In the case of a M. pectoralis minor tension, the reason is often the bent posture. Long and crooked sitting in front of the PC or a generally poor posture with drooping shoulders can lead to a shortening of the muscle, which is associated with fixation and tension of the muscle.

In athletes, the reason can be active overload, insufficient stretching after training, or insufficient training of the antagonists.

Pectoralis minor pain

Pain in the burst can have many causes. From a muscular point of view, it can be an easy one Tension the large or small chest muscle or a pectoralis minor syndrome. This syndrome results in compression of the vessels and nerves below the pectoralis minor muscle.

As described in the ‘Anatomy, section, the vena and subclavian artery run below the insertion of the small pectoral muscle, together with the brachial plexus. A thickening of the muscle can lead to compression of the vessels and nerves. The pain is particularly provoked when the arm is maximally spread and retracted. In addition to the muscular tightness, many patients show a bony tightness due to the course or shape of the coracoid process.

Stretching the small pectoral muscle

The most effective and easiest way to stretch the chest muscles is to stretch against resistance. If you want to stretch the left pectoral muscle, stand next to a door frame with your left arm pointing towards the door frame. Now stretch your left arm upwards and bend it at a 90 ° angle so that your hand is facing up and the palm of your hand is facing forward. The arm bent in this way is now pressed against the door frame, turning the upper body further and further to the right so that the left arm is guided further and further back. This exercise is carried out until the chest feels stretched.